A solid-state image sensor in which pixels are arranged in a two-dimensional lattice to capture images has been used. To improve the resolution of such a solid-state image sensor, a layered pixel structure, in which a photoelectric conversion film and a photodiode are layered, is used. In the layered pixel structure, light having a certain wavelength (e.g., green light) is subject to photoelectric conversion by a photoelectric conversion film, while light having other wavelengths (e.g., red light or blue light) are transmitted through the photoelectric conversion film. The transmitted light is then subject to photoelectric conversion by a photodiode. Photoelectric conversion can be performed for multiple colors of light, whereby the resolution is improved.
To improve sensitivity as well as resolution, a backside-irradiation-type solid-state image sensor, in which the photoelectric conversion film is disposed on a surface (backside) opposite to the surface on which the circuit is disposed in the layered pixel structure, has been proposed (e.g., see PTL 1). In such a solid-state image sensor, a through electrode is provided for each pixel, such that the through electrode penetrates through a silicon layer between the photoelectric conversion film and the circuit surface to transmit an electric signal from the photoelectric conversion film located on the backside to the circuit surface.